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/*
* Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
* Copyright (c) 1996-1999 by Internet Software Consortium.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
* OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* SPDX-License-Identifier: MIT
*/
#include "ares_setup.h"
#ifdef HAVE_NETINET_IN_H
# include <netinet/in.h>
#endif
#ifdef HAVE_ARPA_INET_H
# include <arpa/inet.h>
#endif
#include "ares_nameser.h"
#include "ares.h"
#include "ares_ipv6.h"
#include "ares_private.h"
#ifndef HAVE_INET_NTOP
/*
* WARNING: Don't even consider trying to compile this on a system where
* sizeof(int) < 4. sizeof(int) > 4 is fine; all the world's not a VAX.
*/
static const char *inet_ntop4(const unsigned char *src, char *dst, size_t size);
static const char *inet_ntop6(const unsigned char *src, char *dst, size_t size);
/* char *
* inet_ntop(af, src, dst, size)
* convert a network format address to presentation format.
* return:
* pointer to presentation format address (`dst'), or NULL (see errno).
* note:
* On Windows we store the error in the thread errno, not
* in the winsock error code. This is to avoid losing the
* actual last winsock error. So use macro ERRNO to fetch the
* errno this function sets when returning NULL, not SOCKERRNO.
* author:
* Paul Vixie, 1996.
*/
const char *ares_inet_ntop(int af, const void *src, char *dst,
ares_socklen_t size)
{
switch (af) {
case AF_INET:
return (inet_ntop4(src, dst, (size_t)size));
case AF_INET6:
return (inet_ntop6(src, dst, (size_t)size));
default:
SET_ERRNO(EAFNOSUPPORT);
return (NULL);
}
/* NOTREACHED */
}
/* const char *
* inet_ntop4(src, dst, size)
* format an IPv4 address
* return:
* `dst' (as a const)
* notes:
* (1) uses no statics
* (2) takes a unsigned char* not an in_addr as input
* author:
* Paul Vixie, 1996.
*/
static const char *inet_ntop4(const unsigned char *src, char *dst, size_t size)
{
static const char fmt[] = "%u.%u.%u.%u";
char tmp[sizeof("255.255.255.255")];
if ((size_t)snprintf(tmp, sizeof(tmp), fmt, src[0], src[1], src[2], src[3]) >=
size) {
SET_ERRNO(ENOSPC);
return (NULL);
}
ares_strcpy(dst, tmp, size);
return (dst);
}
/* const char *
* inet_ntop6(src, dst, size)
* convert IPv6 binary address into presentation (printable) format
* author:
* Paul Vixie, 1996.
*/
static const char *inet_ntop6(const unsigned char *src, char *dst, size_t size)
{
/*
* Note that int32_t and int16_t need only be "at least" large enough
* to contain a value of the specified size. On some systems, like
* Crays, there is no such thing as an integer variable with 16 bits.
* Keep this in mind if you think this function should have been coded
* to use pointer overlays. All the world's not a VAX.
*/
char tmp[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")];
char *tp;
struct {
int base, len;
} best, cur;
unsigned int words[NS_IN6ADDRSZ / NS_INT16SZ];
int i;
/*
* Preprocess:
* Copy the input (bytewise) array into a wordwise array.
* Find the longest run of 0x00's in src[] for :: shorthanding.
*/
memset(words, '\0', sizeof(words));
for (i = 0; i < NS_IN6ADDRSZ; i++) {
words[i / 2] |= (unsigned int)(src[i] << ((1 - (i % 2)) << 3));
}
best.base = -1;
best.len = 0;
cur.base = -1;
cur.len = 0;
for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
if (words[i] == 0) {
if (cur.base == -1) {
cur.base = i, cur.len = 1;
} else {
cur.len++;
}
} else {
if (cur.base != -1) {
if (best.base == -1 || cur.len > best.len) {
best = cur;
}
cur.base = -1;
}
}
}
if (cur.base != -1) {
if (best.base == -1 || cur.len > best.len) {
best = cur;
}
}
if (best.base != -1 && best.len < 2) {
best.base = -1;
}
/*
* Format the result.
*/
tp = tmp;
for (i = 0; i < (NS_IN6ADDRSZ / NS_INT16SZ); i++) {
/* Are we inside the best run of 0x00's? */
if (best.base != -1 && i >= best.base && i < (best.base + best.len)) {
if (i == best.base) {
*tp++ = ':';
}
continue;
}
/* Are we following an initial run of 0x00s or any real hex? */
if (i != 0) {
*tp++ = ':';
}
/* Is this address an encapsulated IPv4? */
if (i == 6 && best.base == 0 &&
(best.len == 6 || (best.len == 7 && words[7] != 0x0001) ||
(best.len == 5 && words[5] == 0xffff))) {
if (!inet_ntop4(src + 12, tp, sizeof(tmp) - (size_t)(tp - tmp))) {
return (NULL);
}
tp += ares_strlen(tp);
break;
}
tp += snprintf(tp, sizeof(tmp) - (size_t)(tp - tmp), "%x", words[i]);
}
/* Was it a trailing run of 0x00's? */
if (best.base != -1 &&
(best.base + best.len) == (NS_IN6ADDRSZ / NS_INT16SZ)) {
*tp++ = ':';
}
*tp++ = '\0';
/*
* Check for overflow, copy, and we're done.
*/
if ((size_t)(tp - tmp) > size) {
SET_ERRNO(ENOSPC);
return (NULL);
}
ares_strcpy(dst, tmp, size);
return (dst);
}
#else /* HAVE_INET_NTOP */
const char *ares_inet_ntop(int af, const void *src, char *dst,
ares_socklen_t size)
{
/* just relay this to the underlying function */
return inet_ntop(af, src, dst, size);
}
#endif /* HAVE_INET_NTOP */
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